Smoke Detector drving me crazy...what is the problem??

We have the smoke detectors that are wired into the house and use battery as back up. We built the house 6 years ago and all the batteries in the house have been changed once (my bad...I know). However, the detector in my sons room has issues. Approximately every 6-8 weeks it will start to chirp. I have replaced the 9v battery in there each time. However, the last 2 times I've replaced it...I've tried it in another detector and no problems. (we have nothing else that uses 9v to test in). I just changed his battery 2 weeks ago and it started chirping AGAIN today. It was a new battery 2 weeks ago..just opened the package. I've checked the circuit box downstairs...that seems fine...

Anyone have an insight as to what is going on?? Why is his the only that is chirping? Do I need to get a new one? And since it's electrical I'm sure that means that I need someone to come hook it up for me?

And for the record...I know that at least my kitchen one is working (changed 2 years ago) because my cooking told me so one day LOL!!

Our's did that once too, ironically when our house was also about 6 yrs old only it was the one in our bedroom.

Dh worked two doubles back to back with only 8 hours off in between, so when he came home to sleep and found it doing that, he just unhooked the wiring and took the battery out and we were without one in our bedroom. There was one about 6 feet away outside the bedroom door though. When he got a day off he hooked it back into the wiring and it's never done it again. I'm guessing a wire was just loose and when he reconnected it he got a good connection again.

We had something similar happen - One night in the middle of the night, the smoke alarms went off for about 2 seconds, then they stopped. They did this about 10 times. We started taking them down one by one and figured out that it was the one in the living room making the others go off. We kept it down for a couple weeks, put it back up and it worked fine. We didn't disconnect the wiring or anything. Just took it down like we would to change the battery.

Will vacuum tonight and check for wiring when DH gets home. Leaving the battery out for awhile usually buys me a few days at most before the music starts again. I'm not too concerned about his not being hooked up for a couple days because the next closest smoke detector is right outside his door. The 2 SD are about 3 feet away from each other at most...we have wood floors and so there is a gap under the door for the smoke to escape IF something were to happen and it'd set the hallway one off.

They do expire. I think they are supposed to last about 5 years before expiration. When the time comes to buy new ones that are hard wired, it should be relatively easy to change them out. I think there is a small plug at the end of the wire that comes out of your ceiling and you just need to make sure that the plug fits the new ones you purchase.

We are going to change the ones in our house to combination smoke and carbon monoxcide detectors, but the plugs don't match and my DH hasn't had the chance to make the changes to them yet.